I'm pretty sure I would walk to his spawn point while getting hit by 4 green giants. From what I understand, the behavior being described here is that as long as 4 things are attacking you, a 5th thing you aggro doesn't but instead does...something else? Looks like it just waits around from the descriptions here.
Be careful how this is implemented if it is implemented. As long as you can still build aggro and it swaps over and takes one of the four slots once it becomes higher than the stuff on you, or raid mobs are made immune to this or will run away from their spawn point and force you to chase them/summon you, then its probably ok. As it appears to be described here, this could get really silly.
https://www.project1999.com/forums/s...0&postcount=32 kind of notes people abusing this mechanic, it could definitely be leveraged as described there.